Engine breaks up after 7k? - Honda RC51 Forum : RC51 Motorcycle Forums
 
LinkBack Thread Tools Display Modes
post #1 of 7 (permalink) Old 07-29-2017, 08:12 PM Thread Starter
Senior Member
 
Canty's Avatar
 
Join Date: Mar 2015
Posts: 310
Mentioned: 0 Post(s)
Quoted: 43 Post(s)
Engine breaks up after 7k?

Hey guys, I need some advice. When I ride, I typically keep it under 5k. However, over the last few days I have had the opportunity to open it up a little bit. I noticed right away that after about 6.5-7k the motor breaks up. It still accelerates, but does not sound healthy at all. I have no F1 light, plugs and air filters are less than 500 miles, oil has just been changed. I run high octane fuel only and only on occasions will I run a fuel additive such as Gumout Regain, or Seafoam. The bike does just fine when I am just cruising so it really isn't a big deal for me and my riding style, but if something is wrong I want to address it and fix it. Any ideas where to start? What tests I can run? I have a feeling it is a air/fuel issue but I do not have the equipment to test that at that RPM.

Thanks guys.

2004 RC51
Canty is offline  
Sponsored Links
Advertisement
 
post #2 of 7 (permalink) Old 07-31-2017, 02:57 PM
Senior Member
 
LDH®'s Avatar
 
Join Date: Mar 2010
Posts: 2,217
Mentioned: 7 Post(s)
Quoted: 331 Post(s)
Loose battery connection probably. Put a wrench on the cable bolts and make 100% sure they are guudentight
LDH® is offline  
post #3 of 7 (permalink) Old 08-01-2017, 09:38 AM
Lifetime Premium
 
budoka's Avatar
 
Join Date: Dec 2010
Location: Island Lake Alberta Canada
Posts: 1,904
Mentioned: 11 Post(s)
Quoted: 56 Post(s)
My '82 750 did that when the valves were out of spec. LDH is the Gawd of RC compared to me but might not hurt to check the clearances just to be sure.

Duct tape can't fix stupid...but it sure helps muffle the sound
'03 SP2, '09 GL1800
budoka is offline  
 
post #4 of 7 (permalink) Old 08-01-2017, 01:26 PM
Moderator
 
SubSailor's Avatar
 
Join Date: Oct 2008
Location: Sarasota, FL
Posts: 6,468
Mentioned: 24 Post(s)
Quoted: 89 Post(s)
Any after market exhaust and power commander fitted?
If so, is a good dyno tune used with the power commander?
When I bought my bike years ago, the prior owner must have never had it dyno tuned, as the engine would enter a lean state at around 5800 RPM that grew so bad it would start misfiring until 6800 RPM, ant which point it then ran great.
I had a good dyno tune done on it and it ran perfect afterwards throughout the rev range.
SubSailor is offline  
post #5 of 7 (permalink) Old 08-01-2017, 05:05 PM
Senior Member
 
Join Date: Sep 2015
Location: Edmonton, AB
Posts: 1,522
Mentioned: 7 Post(s)
Quoted: 323 Post(s)
Yeah could be a loose terminal, Could also be low flow from the fuel pump Among other things

Start with the easy stuff. If there is a power commander or similar, disconnect it. Check terminal connections etc
Wibbly is online now  
post #6 of 7 (permalink) Old 08-01-2017, 09:29 PM Thread Starter
Senior Member
 
Canty's Avatar
 
Join Date: Mar 2015
Posts: 310
Mentioned: 0 Post(s)
Quoted: 43 Post(s)
Sorry to not reply quickly...long work week.
No power commander installed currently. Still in the box waiting to be installed.
2 into 1 exhaust from previous owner installed.
All other mods done by me, just the simple ones like the flapper valve and the PAIR mod. Have not done the Soft Rev limiter.
No dyno tune since I took the bike. I am sure it would help and most likely I would find the problem while doing it, I just do not know of a dyno tune location near me.

I am pretty sure my battery cables are tight, I will check next week when I get back home. Valves looked good and sealed good when I rebuilt the motor 2 years ago (less than 1000 miles ago). However, a test to verify pressure is being held and not leaking past the valves couldn't hurt.
Fuel pump was (at time of rebuild) flowing well. I will say that pump has some issues though. Like it always reads low fuel. I doubt this has anything that could inhibit flow and fuel volume or pressure but you guys would know better than I would.

Thanks for the advice thus far. Many of you will be happy to know that I have removed the extended swing arm as you all have said I should and have put on a stock SP2 swing arm.

2004 RC51
Canty is offline  
post #7 of 7 (permalink) Old 08-07-2017, 03:37 PM
Moderator
 
SubSailor's Avatar
 
Join Date: Oct 2008
Location: Sarasota, FL
Posts: 6,468
Mentioned: 24 Post(s)
Quoted: 89 Post(s)
What brand 2-1 exhaust is installed? Jardine?
If so, with no power commander installed, that is probably your problem.
That's the exhaust system installed when I bought my bike, and while it had a power commander installed, I doubt the prior owner ever dyno'd the bike since it was very lean starting at 5800 RPM to where it would stutter and misfire badly (not good). Once past 6200 RPM it ran fine.
After the dyno tune, no further problems. Plugs had a nice honey color on the insulators.
SubSailor is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Honda RC51 Forum : RC51 Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome